The invention relates to a height-adjustable deflection device for the upper fastening point of a three-point belt, a vehicle seat with such a height-adjustable deflection device and a method for the height adjustment of the upper fastening point of a three-point belt.
Commercial vehicle seats in particular are preferably equipped with pneumatically or mechanically sprung vibration-damping systems and thus protect the driver from vibrations of different frequency and amplitude which are unpleasant and harmful to health. A further safety element is the three-point belt. The stationary vehicle-side attachment of the third belt point e.g. to the B-column leads to a clear loss of comfort due to the relative movement between vehicle and seat or driver. Safety and comfort are offered by vehicle seats with a fully integrated three-point belt system, with a belt-end fitting arranged seat-side in the region of the pelvis and, opposite, a seat-belt lock, on the right in the direction of travel, for the driver's side. The shoulder belt outlet is integrated backrest-side and connected to the belt reel of an automatic belt system. A problem with three-point seat belts is that, in the case of a fixed upper fastening point, a sloping shoulder belt cannot operate optimally for different-sized individuals. In order to improve this effect it must therefore be possible for the height of the upper fastening point to be varied.
A height-adjustable deflection device for the upper fastening point of a three-point belt with a holder which can be attached to a supporting member of a vehicle seat is known from JP 2001-158327 A. A deflector which has a reel with a spindle, via which the belt strap of a three-point belt is guided is movably attached in the holder. Parallel to the spindle of the reel, a housing has an outlet slot for the belt strap. Connecting means are formed at the holder and at the deflector such that they engage in form-locking manner with one another in a locked position and do not engage with one another in an adjustment position. The deflector can thus be rotated about a spindle in the adjustment position. The holder has a connecting plate and two supporting brackets, in each of which an oblong hole is formed to receive the spindle of the deflector. However, such a device is not easy to operate and is also not easy to assemble because of the various parts needed.
From DE 35 30 495 A1 a device is known by means of which the height of the upper fastening point can be varied. For this purpose a guide slot running obliquely from top to bottom is formed on the backrest of the vehicle seat. It has a slot opening with a width approximately 3.5 times the width of the seat belt. This makes it possible for the upper fastening point to be located higher or lower depending on the size of the occupant. An improved effect of the three-point belt on the occupant is thereby achieved. However, the seat belt can unintentionally be moved up or down within the guide slot, with the result that the optimum height is not permanently guaranteed. Thus the better effect which is possible in principle may no longer come about under certain circumstances.
A belt retractor is known from U.S. Pat. No. 5,088,794 which has an outlet slot, the height of which can be varied, for the seat belt. The outlet slot is aligned horizontally in a cylindrical casing which is rotated about its central axis. The height of the outlet slot can thus be matched to the person on the vehicle seat. The position of the outlet slot is established via a mechanism in the form of a pivoting lever which is laterally attached to the cylindrical casing. The pivoting lever has a cam with which it engages in one of several recesses in a locking element connected to the cylindrical casing. The pivoting lever releases the cylindrical casing if the pivoting lever is rotated out of its locked position against a spring force by means of an adjusting wheel and thereby causes the cam to come out of the recess. After the cylindrical casing with the outlet slot has been rotated into the correct height, the adjusting wheel is released and the cam enters another recess, with the result that the height of the outlet slot is again fixed. This is a complicated device with many individual parts which must all engage in one another.
Finally, a device is known from EP 1 838 561 B1 by means of which the height of the upper fastening point can be adjusted. For this a deflector which has a reel with a spindle via which the belt strap can be guided, and a housing with an outlet slot for the belt strap, which is aligned parallel to the spindle of the reel is movably attached in a holder. First connecting means are formed at the holder and second connecting means at the deflector which engage in one another in form-locking manner in a locked position and do not engage in one another in an adjustment position, with the result that the deflector can be rotated about the spindle. The spindle of the deflector is pressed into the locked position by means of a spring and the holder has a connecting plate and two supporting brackets, in each of which an oblong hole is formed to receive the spindle of the deflector. The deflector and the reel have a single matching spindle. The height adjustment of the upper fastening point of the three-point belt can thereby be achieved by pressing the deflector backwards against a pressure, rotating it about the spindle and then releasing it again.